What’s Vulnerable › Vulnerabilities

CVE-2011-10018: myBB 1.6.4 Backdoor Arbitrary Command Execution

• Severity: critical (CVSS 9.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 2.9% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2025-08-13 · updated 2026-06-16
• Weakness: CWE-94

Description

myBB version 1.6.4 was distributed with an unauthorized backdoor embedded in the source code. The backdoor allowed remote attackers to execute arbitrary PHP code by injecting payloads into a specially crafted collapsed cookie. This vulnerability was introduced during packaging and was not part of the intended application logic. Exploitation requires no authentication and results in full compromise of the web server under the context of the web application.

Affected products

• mybb: 1.6.4

References

• https://blog.mybb.com/2011/10/06/1-6-4-security-vulnerabilit/
• https://raw.githubusercontent.com/rapid7/metasploit-framework/master/modules/exploits/unix/webapp/mybb_backdoor.rb
• https://web.archive.org/web/20111015224948/http://secunia.com/advisories/46300/
• https://www.exploit-db.com/exploits/17949
• https://www.vulncheck.com/advisories/mybb-backdoor-arbitrary-command-execution
• https://raw.githubusercontent.com/rapid7/metasploit-framework/master/modules/exploits/unix/webapp/mybb_backdoor.rb
• https://www.exploit-db.com/exploits/17949

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